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111 Cards in this Set

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Thick Filaments
contains numerous myosin molecules
Myosin Molecules
which are proteins containing a rol-like tail and two globular heads (crossbridges) and tails.
What do the heads of thick filaments interact with?
special binding sites on the thin filaments
Thin Filaments
made up of globular proteins (G Actin)
Globular Actin
the active site on an actin in thin filaments
What does the G Actin's active site bind to?
myosin heads during contraction
When contractions occur, G actins are binded and polymerized to form?
F Actin
What surrounds the F Actin?
proteins called tropmyosin and troponin
spirals around the stiffens the F Actins
What does Tropomyosin do?
It covers the sctin in binding sites in a relaxed muscle
binds to Ca then changes its shape in order to pull tropomyosin away from the binding sites of actin
What are troponin's subunits?
Tni (binds to actin), TNt (binds tropomyosin) and TNc (binds Ca)
What are skeletal muscle cells stimulated by?
Motor Neurons
Axon Terminals
The axon of each motor neuron branches extensivly to form numerous cellular extentions
Neuromuscular junction
the axon terminals form them with a single muscle fiber
Synaptic cleft
gap between the neurotransmitter and the motor end plate
Motor End Plate
The wrinkly part of the scarcolema
A change in membrane potential such that the cell interior becomes relatively less negative (more positive) than the cell exterior
Action Potenial
contraction; a wave of depolarization down the muscle
resting membrane potential
when the membrane junctions are closed
the destruction of acetycloline prevents continuous contraction
What is polarized at resting potential?
the sarcolemma
Refractory Period
when muscles fibers are insensitive to further stimulation
During contraction what is shortened and reduced
sarcmeres shorten and z lines reduce
What are the roles of Ca on contraction?
makes the nerve impulse able to stimulate the muscle; cross bridges to form
What two intercellular proteins regulate the availability of Ca to enter the cleft?
Calsequestrin and Calmodulin
Calsequestrin and Calmodulin
they alternately release and bind Ca
record muscle contractions
Latent Period
The milliseconds after a muscle is stimulated and excitation-contraction occurs
Contraction Period
when crossbridge formation is occuring
What is muscle derived from?
What are the functions of muscles?
Movement, Heat productions, Maintenance of posture, stabilize joints
Name some examples of movement in muscles
muscle pushes against bone for locomotion, the heart pumps blood through the blood vessles, organs propel food by peristalsis
How is heat production important to muscles?
85% of body heat is produced by skeletal muscle contraction
How is maitenance of posture important to muscles?
constant contractions to counteract gravity
What are the functional characteristics of muscle tissue?
excitability, contractability, extensibility, elasticity
able to be stimulated by nervous impulses; nervous tissue only polarized membranes
What functional characteristics have fibers?
Contractability and Extensibility
able to shorten and thicken
able to strech and extend
able to return to original shape after being streched
Name the types of muscle tissue
skeletal, smooth, and cardiac muscle
Skeletal Muscle
Long theadlike muscle with parallel fibers
Where are skeletal muscles found?
attached to long bones
How much of skeletal muscle is accounted for in the body?
What has short contactions, quick twitch, and has non branching fibers?
Skeletal Muscle
Smooth muscle
spindle shaped cells with no striations
Where are smooth muscles found?
in blood vessles, walls of hollow organs, and GI tract and is associated with peristalsis
What has long contractions and a slow twitch?
Smooth Muscle
Cardiac Muscle
Branched fibers with striations and intercalated disks
Where is cardiac muscle found?
only in the heart
What has intermediate contraction and intermediate twitch?
Cardiac Muscle
a sheath that covers the entire muscle
a sheath that covers each fascicle
a sheath that covers each muscle fiber
What is in between each connective tissue dividing the endomysium?
nerve fibers and blood vessles
Why is muscle highly vascularized?
because muscle uses high amounts of energy to give off large amounts of wastes and bring in more nutrients
Where do muscles span joints and sttach to bones?
at insertion and origin
Indirect attachment (aponeurosis)
muscle fascia extends beyond the muscle and anchors the muscle to the bone or to the fascia to another muscle
Direct attachment (tendon)
epimysium of muscle is fused to periosteum of the bone or perichondrium of cartilage
myofibrils that are divided into contractile units
plasma membrane
cytoplasm; contains glycogen and myoglobin and higher concentrations of mitochondria than other cells
red pigment that stores oxygen
subdivisions of myofibril that has contractile abilities
Sacroplasmic reticulum
smooth ER forming interconnecting tubules surrounding myofibrils
Terminal Cisterna
terminal portions of the sacroplasmic reticulum adjacent to the transverse tubules; stores Ca
Transverse Tubules
tubules running inbetween sarcoplasmic reticulum and penetrating deeply into cells; aides in conducting stimuli into the cell
one T tubule and two terminal cisterna
Name the parts of the sacromere structure
A bands, I bands, Z bands, H zone, M line
A Bands
area overlapping myosin and actin filaments
I Bands
contains actin filaments only
Z Bands
seperates sarcomeres and anchors the thin filaments
H Zone
part of the A band that contains only myosin fibers
M Line
center of the H zone that holds the myosin fibers in place
largest bundles in muscles
Muscle cells (fibers)
divisions of fascicles
divisions of muscle cells
divisions of myofibrils
Name the two types of contractile units
actin and myosin
thin filaments
thick filaments
What type of muscle is innervated?
every cell has a nerve ending
What type of muscle has interterculated disks to control each cell
Name an example of indirect attachment
oblique to abdominals
Contraction Period
when cross bridge period is forming
relaxation period
when Ca is no longer available and no more cross bridges occur
Motor units
motor neurons and all the muscle fibers that it controls
What makes a precise contraction?
the fewer number of fibers in a motor neuron
What determines the strength of a contraction?
the number of motor units being stimulated
What are Graded Muscle Responses established on?
the frequency of stimulation
Twitch Contractions
rapid, jerky contraction in response to a single stimuli
Wave Summation
multipule stimuli occur so there is no time to rest
What stimulation causes larger stimulation
wave summation
smooth sustained contractions with (unfused) or without (fused) partial relaxation
What is the difference between wave summation and tetanus?
Tetanus' frequency of the stimuli is much more rapid
the gradual increase in the force in a contraction of a muscle caused by repetitive stimulation of the same strength after complete relaxation has occured
Muscle Tone
muscle that is always slightly contracted
Name the types of muscle tone
Isotonic Contractions and isometric contractions
Isotonic contractions
tone or tension remains constant; muscle length shortens decreasing the angle of the joint (shrinkage)
How much ATP do you get with ADP and creatine phosphate?
Three times as much creatine can be stored by the cells that ATP (good for 15 sec)
How much ATP do you get from stored glycogen via anerobic pathways?
glycolysis and lactic acid fermentationresulting in 2 ATP (good for 30 - 45 sec)
How much ATP do you get by aerobic respiration?
oxygen is required but 36 can be generated (good for 745 sec)
no ATP so cross bridges can't detach
Insufficient Oxygen
oxygen dept
Build up of Lactic acid
toxic cells and must be converted back into pyruvic acid or else cramping occurs
Heat Production (muscle fatigue)
only 40% of energy released is useful for work; the other 60% is given off as heat
muscle contractions occur because of this; various motor neurons to a whole muscle fire asynchronously
Isometric Contractions
tention increases to peak tention producing capacity but the muscle neither shortens nor lengthens (no shrinkage)
Name an example of Isometric Contraction